scholarly journals Photosynthetic contribution and characteristics of cucumber stems and petioles

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Weike Sun ◽  
Ning Ma ◽  
Hongyu Huang ◽  
Jingwei Wei ◽  
Si Ma ◽  
...  

Abstract Background Photosynthesis in the green leafless blade tissues or organs of plants has been studied in some plants, but the photosynthetic characteristics of stems and petioles are poorly understood. Cucurbitaceous plants are climbing plants that have substantial stem and petiole biomass. Understanding the photosynthetic contribution of cucumber stems and petioles to their growth and the underlying molecular mechanisms are important for the regulating of growth in cucumber production. Results In this study, the photosynthetic capacity of cucumber stems and petioles were determined by 14CO2 uptake. The total carbon fixed by the stems and petioles was approximately 4% of that fixed by one leaf blade in the cucumber seedling stage, while the proportion of the carbon accumulated in the stems and petioles that redistributed to sink organs (roots and shoot apexes) obviously increased under leafless conditions. The photosynthetic properties of cucumber stems and petioles were studied using a combination of electron microscopy and isotope tracers to compare these properties of stems and petioles with those of leaf blade using two genotypes of cucumber (dark green and light green). Compared with those of the leaf blades, the chlorophyll contents of the cucumber stems and petioles were lower, and the stems and petioles had lower chloroplast numbers and lower stoma numbers but higher thylakoid grana lamella numbers and larger stoma sizes. The Chl a/b ratios were also decreased in the petioles and stems compared with those in the leaf blades. The total photosynthetic rates of the stems and petioles were equivalent to 6 ~ 8% of that of one leaf blade, but the respiration rates were similar in all the three organs, with an almost net 0 photosynthetic rate in the stems and petioles. Transcriptome analysis showed that compared with the leaf blades, the stems and petioles has significantly different gene expression levels in photosynthesis, porphyrin and chlorophyll metabolism; photosynthetic antenna proteins; and carbon fixation. PEPC enzyme activities were higher in the stems and petioles than in the leaf blades, suggesting that the photosynthetic and respiratory mechanisms in stems and petioles are different from those in leaf blade, and these results are consistent with the gene expression data. Conclusions In this study, we confirmed the photosynthetic contribution to the growth of cucumber stems and petioles, and showed their similar photosynthetic patterns in the terms of anatomy, molecular biology and physiology, which were different from those of cucumber leaf blades.

2021 ◽  
Author(s):  
Weike Sun ◽  
Ning Ma ◽  
Hongyu Huang ◽  
Jingwei Wei ◽  
Si Ma ◽  
...  

Abstract Background Photosynthesis of plant non-leaf blade green tissue has been studied in some plants, but the photosynthesis characteristics of stem and petiole are poorly understood. Cucurbitaceous plants are climbing plants, and have a large biomass of stem and petiole. Understanding the photosynthetic contribution of cucumber stem and petiole to growth and the underlying molecular mechanisms are important for the regulation of growth in cucumber production. Results Here, the photosynthetic capacity of cucumber stem and petiole were proved by 14CO2 uptake. The total carbon fixation of stem and petioles is around 4% to that of one leaf blade in cucumber seedling stage, while the proportion of carbon accumulated in stem and petioles redistributed to sink organs (root and growing point) is increased obviously under leaf less condition. Photosynthetic properties of cucumber stem and petiole were studied using a combination of electron microscopy, chlorophyll fluorescence imaging and isotope tracer to compare with leaf blade using two genotype of cucumber (dark green and light green stems). Compare with leaf blade, chlorophyll contents of cucumber stem and petiole are lower, and accompanying with lower chloroplast number, lower stoma number, but with higher thylakoid grana lamella number and larger stomata size. The total photosynthetic rate of stem and petiole is equivalent to 6 ~ 8% of one leaf blade, but the respiration rates were simiar in all the three tissues, which shown an almost 0 net photosynthetic rate in stems and petioles, and with lower non-photochemical quenching (NPQ). Transcriptome analysis showed that compared with leaf blade, there are significantly different gene expressions in photosynthesis, porphyrin and chlorophyll metabolism, photosynthetic antenna proteins and carbon fixation in stem and petiole. Although with lower Rubisco expression level in stem and petiole, Rubisco and PEPC enzyme activities were both higher in stem and petiole than in leaf blade, suggesting the photosynthetic and respiratory mechanisms in stem and petiole are different from those in leaf blade. Conclusions In this study, we confirmed the photosynthetic contribution to growth of cucumber stem and petiole, and shown their similar photosynthetic pattern in tissue anatomy, molecular biology and physiology.


1987 ◽  
Vol 44 (12) ◽  
pp. 2102-2117 ◽  
Author(s):  
Russell L. Cuhel ◽  
David R. S. Lean

Sequential 4- to 6-h in situ measurements of carbon dioxide and sulfate uptake showed midday deepening of the depth of Pmax and photoinhibition of upper water column samples. Analysis of subcellular fractions accentuated total uptake measurements, with net protein synthesis providing a direct measure of growth. The percentage of carbon assimilated into protein was smallest at the depth of maximum photosynthesis and increased with light limitation. Summed incubations agreed well with all-day deployments for total carbon fixation and protein synthesis. Assimilation numbers were consistently low (<2.5 g C∙g Chl a−1∙h-1 with integrated (0–20 m) areal production of 616–1467 mg C∙m−2 and 7.5–32.4 mg S∙m−2 during the light day. Nonreductive sulfate assimilation (predominantly ester-SO4−) accounted for up to 40% of the total sulfate uptake when diatoms predominated. Protein synthesis measured with 35S (200–1000 mg protein∙m−2 during the light day) increased 57–89% overnight. Hourly rates were similar during light and scotophase incubations. Night metabolism substantially altered the biochemical composition (e.g. protein, lipid, and carbohydrate) of the plankton with respect to newly incorporated carbon. Combined plant-specific H14CO3− and general microbial 3SSO42− techniques suggested algal dominance in the mixed layer.


2020 ◽  
Vol 145 (3) ◽  
pp. 174-185 ◽  
Author(s):  
Xinyi Chang ◽  
Junli Sun ◽  
Lianling Liu ◽  
Wang He ◽  
Baolong Zhao

Wild jujube (Ziziphus acidojujuba) and cultivated jujube (Ziziphus jujuba) belong to the family Rhamnaceae. Jujubes have marked drought- and salt-tolerant properties. After salt stress, wild jujube seedling growth was inhibited and photosynthetic efficiency was reduced. A bioinformatics approach was used to analyze the transcriptomics data from wild jujube seedlings grown under salt stress, and the genes differentially expressed under the salt stress were identified to provide a theoretical basis for the development and use of wild jujube plantations in salinized soil. The transcriptome sequencing from leaves of wild jujube seedlings was carried out using second-generation sequencing technology. The effects of salt stress on the differential expression of photosynthesis-related genes in wild jujube seedlings were analyzed. Transcriptome sequencing revealed a total of 5269 differentially expressed genes (DEGs), of which 2729 were up-regulated and 2540 were down-regulated. DEGs were mainly enriched with respect to photosynthesis, photosynthetic antenna proteins, glyoxylic acid and dicarboxylic acid metabolism, linolenic acid metabolism, cysteine and methionine metabolism, and porphyrin and chlorophyll metabolism. Among them, the photosynthesis pathway-related DEGs were most highly enriched. Further analysis of porphyrin and chlorophyll synthesis and photosynthesis-related pathways revealed that they were significantly enriched by 97 photosynthesis-related DEGs. The DEGs in the photosynthesis and photosynthetic antenna protein pathways were down-regulated, whereas the DEGs glutamyl-tRNA reductase (HEMA), ferrochelatase (HEMH), and pheophorbide a oxygenase (PAO) in the porphyrin and chlorophyll synthesis pathways were up-regulated, with the remainder being down-regulated. The nuclear gene encoding Rubisco, the key enzyme in the photosynthetic carbon fixation pathway, was also down-regulated. The results showed that the photosynthetic rate of wild jujube seedlings decreased following exposure to salinity stress, an effect that was related to the increased synthesis of 5-aminolevulinic acid and heme, and the up-regulation of expression of a gene encoding a chlorophyll-degrading enzyme, and was related to the down-regulation of gene expression in photosynthesis-related pathways such as light energy capture and carbon fixation. Selection of nine DEGs related to photosynthesis and chlorophyll biosynthesis by quantitative real-time-PCR confirmed that expression changes of these nine DEGs were consistent with the transcriptome sequencing results.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Bo Xiong ◽  
Xia Qiu ◽  
Shengjia Huang ◽  
Xiaojia Wang ◽  
Xu Zhang ◽  
...  

Abstract Citrus species are among the most economically important fruit crops. Physiological characteristics and molecular mechanisms associated with de-etiolation have been partially revealed. However, little is known about the mechanisms controlling the expression and function of genes associated with photosynthesis and chlorophyll biosynthesis in variegated citrus seedlings. The lower biomass, chlorophyll contents, and photosynthetic parameter values recorded for the variegated seedlings suggested that chlorophyll biosynthesis was partially inhibited. Additionally, roots of the variegated seedlings were longer than the roots of green seedlings. We obtained 567.07 million clean reads and 85.05 Gb of RNA-sequencing data, with more than 94.19% of the reads having a quality score of Q30 (sequencing error rate = 0.1%). Furthermore, we detected 4,786 and 7,007 differentially expressed genes (DEGs) between variegated and green Shiranuhi and Huangguogan seedlings. Thirty common pathways were differentially regulated, including pathways related to photosynthesis (GO: 0015979) and the chloroplast (GO: 0009507). Photosynthesis (44 and 63 DEGs), photosynthesis-antenna proteins (14 and 29 DEGs), and flavonoid biosynthesis (16 and 29 DEGs) pathways were the most common KEGG pathways detected in two analyzed libraries. Differences in the expression patterns of PsbQ, PetF, PetB, PsaA, PsaN, PsbP, PsaF, Cluster-2274.8338 (ZIP1), Cluster-2274.38688 (PTC52), and Cluster-2274.78784 might be responsible for the variegation in citrus seedlings. We completed a physiological- and transcriptome-level comparison of the Shiranuhi and Huangguogan cultivars that differ in terms of seedling variegation. We performed mRNA-seq analyses of variegated and green Shiranuhi and Huangguogan seedlings to explore the genes and regulatory pathways involved in the inhibition of chlorophyll biosynthesis and decreases in Chl a and Chl b contents. The candidate genes described herein should be investigated in greater detail to further characterize variegated citrus seedlings.


Plants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2484
Author(s):  
Sunjeet Kumar ◽  
Xinfang Huang ◽  
Gaojie Li ◽  
Qun Ji ◽  
Kai Zhou ◽  
...  

In the agricultural field, blanching is a technique used to obtain tender, sweet, and delicious water dropwort stems by blocking sunlight. The physiological and nutritional parameters of blanched water dropwort have been previously investigated. However, the molecular mechanism of blanching remains unclear. In the present study, we investigated transcriptomic variations for different blanching periods in the stem of water dropwort (pre, mid, post-blanching, and control). The results showed that many genes in pathways, such as photosynthesis, carbon fixation, and phytohormone signal transduction as well as transcription factors (TFs) were significantly dysregulated. Blanched stems of water dropwort showed the higher number of downregulated genes in pathways, such as photosynthesis, antenna protein, carbon fixation in photosynthetic organisms, and porphyrin and chlorophyll metabolism, which ultimately affect the photosynthesis in water dropwort. The genes of hormone signal transduction pathways (ethylene, jasmonic acid, brassinosteroid, and indole-3-acetic acid) showed upregulation in the post-blanched water dropwort plants. Overall, a higher number of genes coding for TFs, such as ERF, BHLH, MYB, zinc-finger, bZIP, and WRKY were overexpressed in blanched samples in comparison with the control. These genes and pathways participate in inducing the length, developmental processes, pale color, and stress tolerance of the blanched stem. Overall, the genes responsive to blanching, which were identified in this study, provide an effective foundation for further studies on the molecular mechanisms of blanching and photosynthesis regulations in water dropwort and other species.


2021 ◽  
Author(s):  
Yuqing Feng ◽  
Yuanyuan Zhao ◽  
Yafei Li ◽  
Jun Zhou ◽  
Yujing Li ◽  
...  

Abstract Nitrate is an important precursor of tobacco-specific nitrosamines (TSNAs) and remarkable difference in nitrate accumulation between lamina and midrib of flue-cured tobacco has long been observed. However, the physiological and molecular mechanisms underpinning this difference remain poorly understood. In this study, physiological and genetic factors impacting nitrate accumulation were identified in pot experiments using flue-cured tobacco K326 with contrasting nitrate content between lamina and midrib. The results showed that three times higher of NO3-N content was observed in midrib than that in lamina, along with lower pigment, NH4-N content, NRA, SSA and GSA in midrib. Transcriptome analysis revealed that expression of genes involved in porphyrin and chlorophyll metabolism, carotenoid biosynthesis, photosynthesis-antenna proteins, photosynthesis, carbon fixation in photosynthetic organisms, starch and sucrose metabolism, nitrogen metabolism and biosynthesis of amino acids were significantly lower in midrib than in lamina. qRT-PCR results showed that the expression level of nitrate transporter genes LOC107782967, LOC107806749, LOC107775674, LOC107829632, LOC107799198, LOC107768465 decreased by 2.74, 1.81, 49.5, 3.5, 2.64 and 2.96 folds while LOC107789301 increased by 8.23 folds in midrib but not in lamina. Reduced chlorophyll content might result in low carbohydrate formation which is the source of energy and carbon skeleton supply, then the low capacity of nitrogen reduction, assimilation and transportation, and the poor ability of nitrate reallocation but high capacity of accumulation might lead to nitrate accumulation in midrib. The results laid the foundation for reducing nitrate content and TSNA formation in tobacco midribs and their products.


2020 ◽  
Vol 10 (23) ◽  
pp. 8565
Author(s):  
Qiang Zhang ◽  
Yi Bai ◽  
Zhi Chen ◽  
Jiezhang Mo ◽  
Yulu Tian ◽  
...  

Lincomycin (LIN), as a waterborne contaminant, may pose a threat to algal health and may affect the provision of ecosystem services. In addition, the molecular mechanisms of lincomycin in algae are still unknown. Here, we attempted to use the transcriptome analysis to elucidate for the first time the potential impact of LIN at an environmentally relevant concentration on the algal growth, and verify the hypothesis that lincomycin can disrupt algal protein synthesis by combining with its subunits of ribosome at high-LIN level. In this study, 7-day growth inhibition tests and RNA-seq sequencing were conducted in Raphidocelis subcapitata (R. subcapitata) in response to a LIN at the concentrations of 0.5 µg L−1 (low), 5 µg L−1 (medium), and 400 µg L−1 (high) treatment groups. A negligible influence on algal growth and merely 21 (21 up- and 0 downregulated) differentially expressed genes (DEGs) was observed at low concentration of LIN, and medium groups showed a 13.4% inhibition and 92 (64 up- and 48 downregulated) DEGs, while high-LIN dosing caused 65.4% reduction in algal growth and 2514 (663 up- and 1851 downregulated) DEGs. In 0.5 and 5 µg L−1 groups, LIN upregulated the genes in the process of photosynthesis consisting of photosynthesis-antenna proteins, and porphyrin and chlorophyll metabolism pathways, suggesting that photosynthesis at low LIN exposure was more sensitive than algal growth. Whereas DEGs in the 400 µg L−1 group were mostly enriched in carbohydrate, carbon fixation in photosynthetic organisms, and nucleotide metabolism pathways. Furthermore, genes involved in detoxification processes were nearly downregulated in high-LIN group. In addition, genes encoding the antioxidant enzymes in the peroxisome pathway such as superoxide dismutase (sod2), peroxin-2 (pex2), 2,4-dienoyl-CoA reductase ((3E)-enoyl-CoA-producing) (decr2) were upregulated, which are responsible for deleting extra intracellular reactive oxygen species (ROS) caused by LIN to protect algal health, suggesting the occurrence of oxidative stress. Taken together, this is the first meticulous study unraveling the molecular mechanism of antibiotics in algae.


Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2903
Author(s):  
Bo Kyung Kim ◽  
Hyoung Min Joo ◽  
Jinyoung Jung ◽  
Boyeon Lee ◽  
Sun-Yong Ha

Rapid climate warming and the associated melting of glaciers in high-latitude open fjord systems can have a significant impact on biogeochemical cycles. In this study, the uptake rates of carbon and nitrogen (nitrate and ammonium) of total phytoplankton and picophytoplankton (<2 μm) were measured in Kongsfjorden in early May 2017 using the dual stable isotope technique. The daily uptake rates of total carbon and nitrogen ranged from 0.3 to 1.1 g C m−2 day−1, with a mean of 0.7 ± 0.3 g C m−2 day−1, and 0.13 to 0.17 g N m−2 day−1, with a mean of 0.16 ± 0.02 g N m−2 day−1. Microphytoplankton (20–200 μm) accounted for 68.1% of the total chlorophyll a (chl-a) concentration, while picophytoplankton (<2 μm) accounted for 19.6% of the total chl-a, with a high contribution to the carbon uptake rate (42.9%) due to its higher particulate organic carbon-to-chl-a ratio. The contributions of picophytoplankton to the total nitrogen uptake rates were 47.1 ± 10.6% for nitrate and 74.0 ± 16.7% for ammonium. Our results indicated that picophytoplankton preferred regenerated nitrogen, such as ammonium, for growth and pointed to the importance of the role played by picophytoplankton in the local carbon uptake rate during the early springtime in 2017. Although the phytoplankton community, in terms of biovolume, in all samples was dominated by diatoms and Phaeocystis sp., a higher proportion of nano- and picophytoplankton chl-a (mean ± SD = 71.3 ± 16.4%) was observed in the relatively cold and turbid surface water in the inner fjord. Phytoplankton production (carbon uptake) decreased towards the inner fjord, while nitrogen uptake increased. The contrast in carbon and nitrogen uptake is likely caused by the gradient in glacial meltwater which affects both the light regime and nutrient availability. Therefore, global warming-enhanced glacier melting might support lower primary production (carbon fixation) with higher degrees of regeneration processes in fjord systems.


2019 ◽  
Vol 26 (39) ◽  
pp. 6976-6990 ◽  
Author(s):  
Ana María González-Paramás ◽  
Begoña Ayuda-Durán ◽  
Sofía Martínez ◽  
Susana González-Manzano ◽  
Celestino Santos-Buelga

: Flavonoids are phenolic compounds widely distributed in the human diet. Their intake has been associated with a decreased risk of different diseases such as cancer, immune dysfunction or coronary heart disease. However, the knowledge about the mechanisms behind their in vivo activity is limited and still under discussion. For years, their bioactivity was associated with the direct antioxidant and radical scavenging properties of phenolic compounds, but nowadays this assumption is unlikely to explain their putative health effects, or at least to be the only explanation for them. New hypotheses about possible mechanisms have been postulated, including the influence of the interaction of polyphenols and gut microbiota and also the possibility that flavonoids or their metabolites could modify gene expression or act as potential modulators of intracellular signaling cascades. This paper reviews all these topics, from the classical view as antioxidants in the context of the Oxidative Stress theory to the most recent tendencies related with the modulation of redox signaling pathways, modification of gene expression or interactions with the intestinal microbiota. The use of C. elegans as a model organism for the study of the molecular mechanisms involved in biological activity of flavonoids is also discussed.


2020 ◽  
Vol 31 (4) ◽  
pp. 716-730 ◽  
Author(s):  
Marc Johnsen ◽  
Torsten Kubacki ◽  
Assa Yeroslaviz ◽  
Martin Richard Späth ◽  
Jannis Mörsdorf ◽  
...  

BackgroundAlthough AKI lacks effective therapeutic approaches, preventive strategies using preconditioning protocols, including caloric restriction and hypoxic preconditioning, have been shown to prevent injury in animal models. A better understanding of the molecular mechanisms that underlie the enhanced resistance to AKI conferred by such approaches is needed to facilitate clinical use. We hypothesized that these preconditioning strategies use similar pathways to augment cellular stress resistance.MethodsTo identify genes and pathways shared by caloric restriction and hypoxic preconditioning, we used RNA-sequencing transcriptome profiling to compare the transcriptional response with both modes of preconditioning in mice before and after renal ischemia-reperfusion injury.ResultsThe gene expression signatures induced by both preconditioning strategies involve distinct common genes and pathways that overlap significantly with the transcriptional changes observed after ischemia-reperfusion injury. These changes primarily affect oxidation-reduction processes and have a major effect on mitochondrial processes. We found that 16 of the genes differentially regulated by both modes of preconditioning were strongly correlated with clinical outcome; most of these genes had not previously been directly linked to AKI.ConclusionsThis comparative analysis of the gene expression signatures in preconditioning strategies shows overlapping patterns in caloric restriction and hypoxic preconditioning, pointing toward common molecular mechanisms. Our analysis identified a limited set of target genes not previously known to be associated with AKI; further study of their potential to provide the basis for novel preventive strategies is warranted. To allow for optimal interactive usability of the data by the kidney research community, we provide an online interface for user-defined interrogation of the gene expression datasets (http://shiny.cecad.uni-koeln.de:3838/IRaP/).


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